Plates configured to rigidly fix fragments of a pars interarticularis to one another

Abstract

An apparatus for securing a vertebra during healing of a fracture within a pars area of the vertebra is described. In certain embodiments, the apparatus is a plate that has an outer shape similar to a shape of a pedicle and/or lamina of the vertebra, and an inner section that facilitates access to the pars area when the plate is secured to the vertebra.

What is claimed: 
     
       1. A bone plate configured to be attached to a single pedicle and a single lamina on the same level of a spinal column, said single lamina including a fractured pars area of a vertebra, the bone plate comprising:
 a monolithic structure defined by a continuous, unbroken elongate peripheral outer rim and a continuous, unbroken elongate peripheral inner rim forming a closed loop, said monolithic structure having an elongate upper surface and an opposing elongate lower bone contacting surface, said upper and lower elongate surfaces connecting said elongate outer rim to said elongate inner rim in a spaced-apart relationship, the outer rim and the inner rim extending alongside each other, said continuous, unbroken peripheral outer rim and inner rim defining a pedicle plate section and a lamina plate section, the outer rim of the pedicle plate section structured to conform to a peripheral contour of the single pedicle of the vertebra and the outer rim of the lamina plate section structured to conform to a peripheral contour of the single lamina of the vertebra such that when the bone plate is implanted the outer rim of the structure extends along a periphery of the single pedicle and the single lamina of the vertebra; 
 wherein the upper surface and the lower bone contacting surface of the pedicle plate section lack screw holes therethrough and wherein said upper surface and said lower bone contacting surface of the lamina plate section include at least one screw hole extending therethrough, the inner rim of the pedicle plate section defining a crescent-shaped pedicle screw receiving hole having a bounded portion surrounded by the inner rim of the pedicle plate section and a non-expandable, narrowed aperture defined by opposing portions of the inner rim at a location between the pedicle plate section and the lamina plate section, the non-expandable, narrowed aperture opens into the pedicle screw receiving hole and opens into a lamina open area defined by the inner rim of the lamina plate section, said non-expandable, narrowed aperture connects said pedicle screw receiving hole with the lamina open area, said bone plate structured to overlie the fractured pars area, 
 wherein a dimension of the non-expandable narrowed aperture between opposing portions of the inner rim is less than a dimension of the pedicle screw receiving hole between opposing portions of the inner rim of the pedicle plate section and a dimension of the lamina open area between opposing portions of the inner rim of the lamina plate section; 
 the lower bone contacting surface of the pedicle plate section configured to conform to a three dimensional geometry of a surface of the single pedicle of the vertebra and the lower bone contacting surface of the lamina plate section configured to conform to a three dimensional geometry of the single lamina; and 
 a pedicle screw received in said pedicle screw receiving hole and configured to fix the pedicle plate section to the pedicle of the vertebra such that when the pedicle screw is fully seated in the pedicle screw receiving hole the pedicle screw is configured not to deform the pedicle plate section and the narrowed aperture; and 
 wherein a total surface area between the outer rim and the inner rim of the pedicle plate section is less that a total surface area between the outer rim and the inner rim of the lamina plate section; and 
 further wherein a total surface area defined by the pedicle screw receiving hole is less than a total surface area of the lamina plate open area. 
 
     
     
       2. The bone plate of  claim 1 , further comprising at least one lamina screw received through said at least one screw hole extending through the upper surface and the lower bone contacting surface of the lamina plate section. 
     
     
       3. The bone plate of  claim 1 , further comprising at least one spinous process screw received through said at least one screw hole extending through the upper surface and the lower bone contacting surface of the lamina plate section.